/* Copyright (c) 2009 Nordic Semiconductor. All Rights Reserved.
 *
 * The information contained herein is property of Nordic Semiconductor ASA.
 * Terms and conditions of usage are described in detail in NORDIC
 * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
 *
 * Licensees are granted free, non-transferable use of the information. NO
 * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
 * the file.
 *
 */


#include <stdint.h>
#include <stdbool.h>

#include "cherry8x16.h"
#include "nrf.h"

#define CHERRY8x16_NUM_OF_COLUMNS 16 //!< Number of columns in the keyboard matrix
#define CHERRY8x16_NUM_OF_ROWS 8 //!< Number of rows in the keyboard matrix

#define MODIFIER_HID_START 0xE0
#define MODIFIER_HID_END   0xE7
static uint8_t m_currently_pressed_keys[CHERRY8x16_MAX_NUM_OF_PRESSED_KEYS]; //!< Array holding currently pressed keys. Filled up from index 0. Values are
static uint8_t m_transmitted_keys[CHERRY8x16_MAX_NUM_OF_PRESSED_KEYS]; //!< Array holding the keys that have already been transmitted.
static uint8_t m_num_of_currently_pressed_keys; //!< Number of keys in m_currently_pressed_keys
static uint8_t m_number_of_transmitted_keys; //!< Number of keys in m_transmitted_keys

static uint8_t m_key_packet[KEY_PACKET_SIZE]; //!< Stores last created key packet. One byte is used for modifier keys, one for OEMs. Key values are USB HID keycodes.

static const uint8_t volatile * m_row_port; //!< Pointer to location where row IO can be read
static uint16_t volatile * m_column_port; //!< Pointer to location where column IO can be written
static const uint8_t * matrix_lookup; //!< Pointer to the key lookup matrix in use

/** Table containing the mapping between the key matrix and the HID Usage codes for each key. */
static const uint8_t default_matrix_lookup[CHERRY8x16_NUM_OF_COLUMNS*CHERRY8x16_NUM_OF_ROWS] =
{
  0xE7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0xE3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0xE0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0xE1, 0xE6, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0xE2, 0xE5, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x29, 0x3E, 0x3D, 0x3C, 0x3B, 0x3A, 0x3F, 0x40,
  0x1E, 0x23, 0x22, 0x21, 0x20, 0x1F, 0x24, 0x25,
  0x4F, 0x43, 0x47, 0x53, 0x46, 0x48, 0x42, 0x41,
  0x51, 0x2D, 0x2E, 0x2A, 0x00, 0x4A, 0x27, 0x26,
  0x52, 0x13, 0x2F, 0x30, 0x00, 0x4B, 0x12, 0x0C,
  0x50, 0x33, 0x34, 0x32, 0x28, 0x4E, 0x0F, 0x0E,
  0x2C, 0x38, 0x4C, 0x49, 0x65, 0x4D, 0x37, 0x36,
  0x35, 0x05, 0x19, 0x06, 0x1B, 0x1D, 0x11, 0x10,
  0x39, 0x0A, 0x09, 0x07, 0x16, 0x04, 0x0B, 0x0D,
  0x2B, 0x17, 0x15, 0x08, 0x1A, 0x14, 0x1C, 0x18
};

static bool cherry8x16_have_keys_changed(const uint8_t *state_now, uint8_t number_of_now_pressed_keys, const uint8_t *state_before, uint8_t number_of_before_pressed_keys);
static bool cherry8x16_keymatrix_read(uint8_t *pressed_keys, uint8_t *number_of_pressed_keys);
static void cherry8x16_keypacket_addkey(uint8_t key);
static void cherry8x16_keypacket_create(uint8_t *key_packet, uint8_t key_packet_size);
static void cherry8x16_remap_fn_keys(uint8_t *keys, uint8_t number_of_keys);
static uint8_t cherry8x16_row_read(void);

cherry8x16_status_t cherry8x16_init(const uint8_t volatile * row_port, uint16_t * column_port, const uint8_t * key_lookup_matrix)
{
  cherry8x16_status_t status = CHERRY8x16_OK;

  if (row_port == 0 || column_port == 0)
  {
    status = CHERRY8x16_INVALID_PARAMETER;
  }
  else
  {
    m_row_port = row_port;
    m_column_port = column_port;

    *m_column_port = 0x0000;
    if (*m_row_port != 0x00)
    {
      status = CHERRY8x16_NOT_DETECTED;
    }
    else
    {
      m_num_of_currently_pressed_keys = 0;
      m_number_of_transmitted_keys = 0;

      for (uint_fast8_t i = CHERRY8x16_MAX_NUM_OF_PRESSED_KEYS; i--;)
      {
        m_currently_pressed_keys[i] = 0;
        m_transmitted_keys[i] = 0;
      }
    }

    if (key_lookup_matrix == CHERRY8x16_DEFAULT_KEY_LOOKUP_MATRIX)
    {
      matrix_lookup = default_matrix_lookup;
    }
    else
    {
      matrix_lookup = key_lookup_matrix;
    }
  }

  return status;
}

bool cherry8x16_new_packet(const uint8_t ** p_key_packet, uint8_t *p_key_packet_size)
{
  bool new_packet_prepared;

  // Save currently pressed keys
  for (uint_fast8_t i = CHERRY8x16_MAX_NUM_OF_PRESSED_KEYS; i--;)
  {
    m_transmitted_keys[i] = m_currently_pressed_keys[i];
  }
  m_number_of_transmitted_keys = m_num_of_currently_pressed_keys;

  // Create a new packet if key states have changed and there are no keys blocking each other (ghosting/phantom keys)
  if (cherry8x16_keymatrix_read(m_currently_pressed_keys, &m_num_of_currently_pressed_keys))
  {
    if (cherry8x16_have_keys_changed(m_currently_pressed_keys, m_num_of_currently_pressed_keys, m_transmitted_keys, m_number_of_transmitted_keys))
    {
      cherry8x16_keypacket_create(&m_key_packet[0], KEY_PACKET_SIZE);
      *p_key_packet = &m_key_packet[0];
      *p_key_packet_size = KEY_PACKET_SIZE;
      new_packet_prepared = true;
    }
    else
    {
      // The same keys are still pressed, no need to create a new packet
      new_packet_prepared = false;
    }
  }
  else
  {
    // Ghosting detected. Don't create a packet.
    new_packet_prepared = false;
  }

  return new_packet_prepared;
}


/**
 * @brief Function for reading and returning keyboard matrix row state.
 *
 * @return uint8_t Row state
 */
static uint8_t cherry8x16_row_read(void)
{
  return *m_row_port;
}

/**
 * @brief Function for reading the keyboard matrix state and stores the pressed keys to an array.
 *
 * This function resolves keys from the matrix and finds their corresponding HID usage codes
 * If there are any ghost key conditions the packet will be discarded
 * @param pressed_keys Array holding pressed keys. Must be at least CHERRY8x16_MAX_NUM_OF_PRESSED_KEYS in size.
 * @param number_of_pressed_keys Pointer to variable where number of pressed keys will be stored.
 * @return
 * @retval true If no keys were blocking each other.
 * @retval false If some keys were blocking each other o rno key is pressed.
 */
static bool cherry8x16_keymatrix_read(uint8_t *pressed_keys, uint8_t *number_of_pressed_keys)
{
  uint_fast8_t row_state[CHERRY8x16_NUM_OF_COLUMNS];
  uint_fast8_t blocking_mask = 0;

  *number_of_pressed_keys = 0;

  for (uint_fast8_t column = CHERRY8x16_NUM_OF_COLUMNS; column--;)
  {
    // drive column under test
    *m_column_port = (uint16_t)(1UL << column);
    row_state[column] = cherry8x16_row_read();

    // Check if any keys are pressed
    if (row_state[column] != 0)
    {
      uint_fast8_t detected_keypresses_on_column = 0;

      // Loop through rows, check for active rows and add pressed keys to the array
      for (uint_fast8_t row = CHERRY8x16_NUM_OF_ROWS; row--;)
      {
        if (row_state[column] & (1U << row))
        {
          if (*number_of_pressed_keys < CHERRY8x16_MAX_NUM_OF_PRESSED_KEYS)
          {
            *pressed_keys = matrix_lookup[column*CHERRY8x16_NUM_OF_ROWS + row];
            pressed_keys++;
            (*number_of_pressed_keys)++;
          }
          detected_keypresses_on_column++;
        }
      }

      if (detected_keypresses_on_column > 1)
      {
        if (blocking_mask & row_state[column])
        {
          // Cannot determine reliably all pressed keys, two or more keys are blocking each other.
          return false;
        }
      }
      blocking_mask |= row_state[column];
    }
  }

  return true;
}

/**
 * @brief Function for remapping the keypad, F11 and F12 keys in case when Fn key is pressed.
 *
 * @param keys Array holding pressed keys.
 * @param number_of_keys Number of elements if 'keys' array.
 */
static void cherry8x16_remap_fn_keys(uint8_t *keys, uint8_t number_of_keys)
{

  /*lint -e845 -save // A zero has been given as right argument to operator '<<'" */
  /*lint -e778 -save // Constant expression evaluates to zero */

#define MODIFIER_LEFT_CONTROL_HID  0xE0
#define MODIFER_RIGHT_CONTROL_HID  0xE4
  // Check if Fn key is pressed along with any other modifier key (only usage now is Fn+Left_Ctrl = Right Ctrl)
  // So we modify the modifier byte if Fn+Left_Ctrl is pressed, HID for left_Ctrl = 0xE0
  if ( keys[0] & (1UL<<(MODIFIER_LEFT_CONTROL_HID-MODIFIER_HID_START)) )
  {
    keys[0] &= ~(1UL<<(MODIFIER_LEFT_CONTROL_HID-MODIFIER_HID_START));
    keys[0] |= (1UL<<(MODIFER_RIGHT_CONTROL_HID-MODIFIER_HID_START));
  }

  /*lint -restore */
  /*lint -restore */

  for (uint_fast8_t i = 2; i < number_of_keys; i++)
  {
    switch (keys[i])
    {
      case 0x10: //'M'
        keys[i] = 0x62; //Keypad 0
        break;
      case 0x37: //'>'
        keys[i] = 0x63; //Keypad .
        break;
      case 0x38: //'/'
        keys[i] = 0x54; //Keypad /
        break;
      case 0x0D: //'J'
        keys[i] = 0x59; //Keypad 1
        break;
      case 0x0E: //'K'
        keys[i] = 0x5A; //Keypad 2
        break;
      case 0x0F: //'L'
        keys[i] = 0x5B; //Keypad 3
        break;
      case 0x33: //''
        keys[i] = 0x57; //Keypad +
        break;
      case 0x28: //'Enter'
        keys[i] = 0x58; //Keypad enter
        break;
      case 0x18: //'U'
        keys[i] = 0x5C; //Keypad 4
        break;
      case 0x0C: //'I'
        keys[i] = 0x5D; //Keypad 5
        break;
      case 0x12: //'O'
        keys[i] = 0x5E; //Keypad 6
        break;
      case 0x13: //'P'
        keys[i] = 0x56; //Keypad -
        break;
      case 0x24: //'7'
        keys[i] = 0x5F; //Keypad 7
        break;
      case 0x25: //'8'
        keys[i] = 0x60; //Keypad 8
        break;
      case 0x26: //'9'
        keys[i] = 0x61; //Keypad 9
        break;
      case 0x27: //'0'
        keys[i] = 0x55; //Keypad *
        break;
      case 0x3A: //'F1'
        keys[i] = 0x44; //'F11'
        break;
      case 0x3B: //'F2'
        keys[i] = 0x45; //'F12'
        break;
      default:
        break;
    }
  }
}

/**
 * @brief Function for determining whether the keyboard matrix state has changed compared to the state before.
 *
 * @param state_now List of pressed keys in current state
 * @param number_of_now_pressed_keys Number of pressed keys in current state
 * @param state_before List of pressed keys in previous state
 * @param number_of_before_pressed_keys Number of pressed keys in previous state
 * @return
 * @retval true If keyboard matrix is different compared to state before.
 * @retval false If keyboard matrix is the same compared to state before.
 */
static bool cherry8x16_have_keys_changed(const uint8_t *state_now, uint8_t number_of_now_pressed_keys, const uint8_t *state_before, uint8_t number_of_before_pressed_keys)
{
  if (number_of_now_pressed_keys != number_of_before_pressed_keys)
  {
    return true;
  }
  else
  {
    for (uint_fast8_t i = number_of_now_pressed_keys; i--;)
    {
      if (state_now[i] != state_before[i])
      {
        return true;
      }
    }
  }
  return false;
}

/**
 * @brief Function for adding a key to the key packet.
 *
 * If key is found to be in the packet, it will not be added twice.
 * Attempts to add more keys than the buffer capacity allows will be silently ignored.
 *
 * @param key Key to add
 */
static void cherry8x16_keypacket_addkey(uint8_t key)
{
  for (uint_fast8_t i = KEY_PACKET_KEY_INDEX; i < KEY_PACKET_SIZE; i++)
  {
    if (m_key_packet[i] == key)
    {
      return;
    }
  }

  for (uint_fast8_t i = KEY_PACKET_KEY_INDEX; i < KEY_PACKET_SIZE; i++)
  {
    if (m_key_packet[i] == KEY_PACKET_NO_KEY)
    {
      m_key_packet[i] = key;
      return;
    }
  }
}

/**
 * @brief Function for creating a new key packet.
 *
 * This function uses @ref m_currently_pressed_keys to determine pressed keys.
 * Priority is given to those keys that were found in the previous packet.
 * All modifier keys can be found in all packets.
 * If Fn key is detected to be pressed, some keys are remapped to different functions.
 *
 * @param key_packet Pointer to location where packet contents will be put
 * @param key_packet_size Key packet size in bytes
 */
static void cherry8x16_keypacket_create(uint8_t *key_packet, uint8_t key_packet_size)
{
  // Clear key_packet contents
  for (uint_fast8_t i = KEY_PACKET_KEY_INDEX; i < key_packet_size; i++)
  {
    key_packet[i] = KEY_PACKET_NO_KEY;
  }
  key_packet[KEY_PACKET_MODIFIER_KEY_INDEX] = 0;
  key_packet[KEY_PACKET_RESERVED_INDEX] = 0;

  // Give priority to keys that were already pressed when we transmitted them the last time.
  for (uint_fast8_t i = 0 ; i < m_number_of_transmitted_keys; i++)
  {
    for (uint_fast8_t j = 0; j < m_num_of_currently_pressed_keys; j++)
    {
      if (m_transmitted_keys[i] == m_currently_pressed_keys[j])
      {
        cherry8x16_keypacket_addkey(m_currently_pressed_keys[j]);
        break;
      }
    }
  }

  bool fn_key_is_set = false;

  // Detect if Fn is pressed, detect modifier keys, and add rest of the keys to the packet
  for (uint_fast8_t i = 0; i < m_num_of_currently_pressed_keys; i++)
  {
    if (m_currently_pressed_keys[i] == 0xFF) // Pressing Fn key changes function of certain keys and it must handled by the firmware
    {
      fn_key_is_set = true;
    }
    // Modifier HID usage codes are from 0xE0 to 0xE7
    else if (m_currently_pressed_keys[i] >= MODIFIER_HID_START && m_currently_pressed_keys[i] <= MODIFIER_HID_END) // Detect and set modifier keys
    {
      key_packet[KEY_PACKET_MODIFIER_KEY_INDEX] |= (uint8_t)(1U << (m_currently_pressed_keys[i] - MODIFIER_HID_START));
    }
    else if (m_currently_pressed_keys[i] != 0)
    {
      cherry8x16_keypacket_addkey(m_currently_pressed_keys[i]);
    }
  }

  if (fn_key_is_set)
  {
    cherry8x16_remap_fn_keys(&key_packet[0], KEY_PACKET_MAX_KEYS);
  }
}
